The present disclosure relates to an air conditioner and a control method thereof.
Air conditioners are home appliances that maintain indoor air into the most proper state according to use and purpose thereof. For example, such an air conditioner controls indoor air into a cold state in summer and controls indoor air into a warm state in winter. Furthermore, the air conditioner controls humidity of the indoor air and purifies the indoor air to become into a pleasant and clean state. In detail, the air conditioner has a refrigeration cycle in which compression, condensation, expansion, and evaporation processes for a refrigerant are performed. Thus, a cooling or heating operation of the air conditioner may be performed to cool or heat the indoor air according to the refrigeration cycle.
Such an air conditioner may be classified into a split type air conditioner in which indoor and outdoor units are separated from each other and an integral type air conditioner in which indoor and outdoor units are integrally coupled to each other as a single device, according to whether the indoor and outdoor units are separated from each other. The outdoor unit includes an outdoor heat exchanger heat-exchanging with external air, and the indoor unit includes an indoor heat exchanger heat-exchanging with indoor air. The air conditioner may be operated in a cooling mode or heating mode which are converted into each other.
When the air conditioner is operated in the cooling mode, the outdoor heat exchanger serves as a condenser, and the indoor heat exchanger serves as an evaporator. On the other hand, when the air conditioner is operated in the heating mode, the outdoor heat exchanger serves as an evaporator, and the indoor heat exchanger serves as a condenser.
FIG. 7 illustrates a pressure-enthalpy (p-h) diagram of a refrigerant cycle according to a related art. Referring to FIG. 7, a refrigerant is introduced into a compressor in a state “a”, and then is compressed in the compressor and discharged in a state “b”. Thereafter, the refrigerant is introduced into a condenser. The refrigerant in the state “b” may be in a liquid phase.
Then, the refrigerant is condensed in the condenser and discharged in a state “c”. Thereafter, the refrigerant is throttled in an expansion device, and thus is changed into a state “d”, i.e., a two-phase state. The refrigerant throttled in the expansion device is introduced into an evaporator. Then, the refrigerant is heat-exchanged in the evaporation, and thus is changed into the state “a”. The refrigerant in the state “a” may be in a gaseous phase. Thus, the gaseous refrigerant is introduced into the compressor. The above-described refrigerant cycle is repeatedly performed.
According to the related art, cooling or heating performance may be limited.
In detail, when an external air condition is bad, that is, external air around an area on which the air conditioner is installed has a very high or low temperature, sufficient refrigerant circulation amount should be secured so as to obtain desired cooling/heating performance.
For this, a compressor having large capacity should be provided so as to increase performance of the compressor. In this case, there is a limitation that manufacturing or installation costs of the air conditioner are increased.
In addition, when the refrigerant discharged from the condenser is in an overcooled state, that is, overcooling of the refrigerant is secured, even though evaporation performance of the evaporator, i.e., a lower area of a line connecting a point “d” to a point “a” may be increased, it may be difficult to secure the overcooling of the refrigerant in a system of FIG. 6. Thus, it may be difficult to expect performance improvement.